350 pushrods

Discussion in 'Small Block Tech' started by Jeff Pulera, Nov 6, 2019.

  1. Jeff Pulera

    Jeff Pulera Well-Known Member

    Just installed new mild cam and hydraulic flat tappet set in 1968 350 engine. Ran engine for cam break-in and it sounds like a couple of rockers are trying to escape the valve covers!

    Going to remove rocker covers tonight and inspect for loose pushrods, check pushrod rotation when running, etc.

    I'd not been able to find 350 engine building guides online so just winged it. I tried to reinstall pushrods in same direction i removed them but a couple may have gotten flipped end for end. They appeared to be the same at both ends so went with it.

    And torquing rocker shafts i just went back and forth and gradually tightened them so as not to force any one shaft bolt against valve spring pressure.

    Did i mess up? Any tips appreciated, going to tackle this after work tonight. Hoping I didn't lose any cam lobes, appears to run smooth but unhappy with the lifter noise that sounds like maybe one on each bank are clattering.

    Thanks
    Jeff
     
  2. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Any time you change the cam you should check for proper push rod length. You do this with an adjustable push rod. This one will work,

    https://www.summitracing.com/parts/tfs-9002/overview/

    I would check multiple positions in the engine, certainly all for corner push rods. Measure, and then order the correct length.

    PushrodMeasurement..jpg

    The rocker pedestal bolts need to be torqued down to 25 ft. lbs. with a reliable torque wrench. You should also check your rocker arms and shafts for wear, which is very common.

    When you check for push rod length, the valve needs to be closed. The easiest way is to mark your balancer in 90* increments, which is every 5.25". Start with #1 cylinder. Take the distributor cap off and rotate the balancer until the rotor is pointing at the #1 tower of the cap. Check the 2 valves of cylinder 1, then rotate the engine 90* and check the next cylinder in the firing order (#8). Follow the firing order, 1-8-4-3-6-5-7-2.
     
    Darron72Skylark likes this.
  3. MrSony

    MrSony Well-Known Member

    Didn't 68/69 use specific lifters and pushrods?
     
  4. Jeff Pulera

    Jeff Pulera Well-Known Member

    So good news - running engine with valve covers off, rockers humming like a sewing machine, all pushrods rotating. The noises that appeared to be coming from valve covers now seem to be leaky manifold donuts on both sides. Very misleading when listening.

    Great advice and description of how to set pushrod lengths, thank you, but for now not going to tear it down again, running smooth. Once I get RPMs up a bit past that loping idle the noises go away.

    Thanks

    Jeff
     
    MrSony likes this.
  5. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Different than 70 and up but you still need to measure.
     

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